The towers currently used for supporting wind turbines having capacities up to 750 Kw, either lattice towers or tubular towers, are usually erected in sections by a crane and assembled in the vertical position, joining each section of the tower to the adjacent tower sections by means of bolted connections. The nacelle and the rotor are then mounted on top of the vertically oriented tower using cranes.
As the tower height increase, the costs of the installation of wind turbines also increase. The large cranes that are needed involve high transportation and rental costs. On the other hand the size of large cranes involve spatial requirements on the installation site that may be difficult to comply with.
The prior art shows a number of proposals for erecting wind turbine without the use of large cranes such as the following.
US 2002/0095878 discloses a tower constructed of telescopic sections with the lowermost section having an edge portion pivotally connected to a foundation to enable the tower sections to be transported to the site of installation. The tower sections are assembled at the installation site in a nested relationship, each within the adjacent lower tower section. The nacelle and the rotor are mounted on the upper end of the uppermost tower section and the nested tower sections are then tilted upwardly to a vertical position. After the tower is tilted to its vertical position and securely connected to the foundation, the telescopic tower sections are vertically extended to position the wind turbine in a vertically elevated position.
US 2004/0045226 discloses a tower divided into an upper section with a tower top and a lower section with a tower bottom. The sections are hinged together. The lower section is hinged to a tower base. A telescoping crane is attached to a lift point on the lower section. The crane is extended to lift the sections to the vertical position with the lower section resting on the base and the tower top of the upper section near ground level. The wind turbine drivetrain is attached to the tower top end using a small ground crane while the tower top of the upper section is near ground level. The telescoping crane is attached to another lift point on the upper section to partially lift the upper section, which is supported in this position. The telescoping crane is relocated and reattached to the lift point on the upper section. The telescoping crane is fully extended to raise the upper section and the wind turbine drive train to vertical above the lower section.
CA 2418021 discloses a tower comprising a plurality of pivotally interconnected tower tubular sections, and a tower erection method not requiring the use of a crane. The tower tubular sections are assembled at the ground level of the installation site by interconnecting the adjacent sections with hinges, with the base tower section temporarily hinged to the tower foundation. Winch assemblies secured to the tower foundation are activated to pull on winch cables attached to the hinged tubular tower sections to lift and tilt the tubular tower sections upwardly, in sequence using, in part, the ground surface vertical forces counter-acting the weight of the tower at the contact points with the ground.
The wind industry demands constantly wind turbine towers allowing erecting methods of wind turbines without using larger cranes and the present invention is intended to satisfy said demand.